CVE-2025-15104: Nu Html Checker (validator.nu) - Restriction bypass vulnerability allowing local SSRF
Nu Html Checker (validator.nu) contains a restriction bypass that allows remote attackers to make the server perform arbitrary HTTP/HTTPS requests to internal resources, including localhost services. While the validator implements hostname-based protections to block direct access to localhost and 127.0.0.1, these controls can be bypassed using DNS rebinding techniques or domains that resolve to loopback addresses.This issue affects The Nu Html Checker (vnu): latest (commit 23f090a11bab8d0d4e698f1ffc197a4fe226a9cd).
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2025-15104?
The severity of CVE-2025-15104 is critical as it allows attackers to exploit the vulnerability for local SSRF attacks.
How do I fix CVE-2025-15104?
To fix CVE-2025-15104, update to the latest version of Nu Html Checker as the fix is included in recent updates.
What types of requests can be made due to CVE-2025-15104?
CVE-2025-15104 allows attackers to make arbitrary HTTP/HTTPS requests to both internal resources and localhost services.
Are there any exploit examples for CVE-2025-15104?
Yes, exploit examples for CVE-2025-15104 typically demonstrate the ability to access sensitive internal services.
How can I detect if my system is vulnerable to CVE-2025-15104?
You can detect vulnerability to CVE-2025-15104 by scanning your installation of Nu Html Checker for outdated versions that lack the security fix.